assume cs:code
code segment
start: mov ax,0b800h
       mov es,ax
       mov di,160*12
       mov bx,offset s-offset se
       mov cx,80
    s: mov byte ptr es:[di],'!'
       add di,2
       int 7ch
   se: nop
       mov ax,4c00h
       int 21h
code ends
end start
